The present invention relates to a vehicle control system for ensuring a desired vehicle behavior during braking.
During braking, a vehicle planar motion represented by a vehicle yaw rate and a side slipping motion is affected by characteristic changes such as a change in a tire cornering power due to weight transfer during braking and a decrease in a cornering force due to a braking force produced at a tire contact portion. Therefore, the steering response characteristic during braking is considerably different from the characteristic during constant speed conering operations. Drivers are often bewildered by unexpected vehicle behavior during braking.
Furthermore, an unexpected yawing motion is produced by brake application during a straight ahead operation if the balance in the fricition coefficient of a brake pad between left and right wheels is lost.
Japanese Utility Model Provisional Publication No. 59-155164 discloses a brake control system. This brake control system is designed to increase a vehicle yawing response during braking by retarding an increase of the brake fluid pressure for the outside wheel of a turn with respect to an increase of the brake fluid pressure for the inside wheel if the steering angle becomes equal to or greater than a predetermined value during braking. However, this brake control system is not designed to compensate for changes in the vehicle characteristics.